黑河新生地区早白垩世花岗质岩石的锆石U--Pb年龄、地球化学特征及地质意义  

Zircon U-Pb ages,geochemistry features and its geological implication of Early Cretaceous granites in Xinsheng area of Heihe City

作　　者：朱怀亮[1] 陈跃军[2] 吴国学[1] 李云峰[2] 张宇峰[3] 吴涛涛[4] 刘永俊[1] 王长兵[1] 刘雪松[1,5] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学古生物学与地层学研究中心,长春130026 [3]内蒙古自治区地质调查院,呼和浩特010020 [4]沈阳地质调查中心,沈阳110034 [5]吉林大学地质博物馆,长春130026

出　　处：《世界地质》2013年第4期665-680,共16页World Geology

基　　金：中国地质调查局项目(1212011220440);黑龙江省国土资源厅项目(HLJKD2007-07)联合资助

摘　　要：黑河新生地区位于大、小兴安岭的结合部,其早白垩世岩浆活动频繁,主要岩石类型为花岗斑岩、花岗闪长岩。地球化学特征显示这些岩石为高钾钙碱性系列的I型花岗岩,富集大离子亲石元素(LILE)而亏损高场强元素(HFSE)。LA--ICPMS锆石U--Pb年龄测定结果表明,花岗斑岩的形成时代为118.1±1.5 Ma,花岗闪长岩的形成时代为112.8±0.9 Ma,这与该区广泛分布的早白垩世火山岩形成时代一致。Hf同位素成分特征表明,岩体的源岩为中—新元古代时期由亏损地幔起源的火成岩。结合岩石学特征和邻区其他地质资料,认为黑河新生地区早白垩世花岗岩的形成与古太平洋板块的俯冲作用有关。Xinsheng area of Heihe is located in the boundary area of Great Xing＇an Range and Lesser Xing＇an Range Mts, where the Early Cretaceous magmatic activity was frequently. The rocks are mainly composed of granite porphyry and granodiorite, with geochemical characteristics of high-K calc-alkaline I-type granite series, which enrichment in large-ion lithophile elements （LILE） and depletion in high field strength elements （HFSE）. The U- Pb dating results confirmed by LA-ICPMS indicated that granite porphyry and granodiorite were emplaced at 118.1 ± 1.5 Ma and 112. 8± 0. 9 Ma, respectively, which were consistented with the stages of volcanic rocks. Character- istics of zircon Hf isotopic indicated that the source rocks of Early Cretaceous granites were igneous rocks originated from depleted mantle of Mid-Neo Proterozoic. i2ombining with their petrography and geological data of adjacent re- gions, the authors proposed that Early Cretaceous granites might be closely related to the subduction of paleo-Pacific tectonic plate.

关 键 词：早白垩世花岗岩 锆石U—Pb年龄 地球化学 地质意义 黑河新生地区 

分 类 号：P534.53[天文地球—古生物学与地层学] P597.3[天文地球—地质学]